One-Pot Synthesis of 1,2,4-Oxadiazoles Mediated by Microwave Irradiation under Solvent-Free Condition

Oxadiazoles

“…The diagnostic fragmentation pattern of 1,2,4-oxadiazoles is a 1,3-dipolar cycloreversion process, which proceeds via initial cleavage of the 1,5 (CÀO) and 3,4 (CÀN) [175,176].…”

“…A wide variety of carboxylic acid derivatives can be used for the formation of Oacylated amidoximes, such as esters [196], acid chlorides [152,154,171,175,187,197], [197b, 152, 171, 198], including symmetrical acid anhydrides derived from amino acids [184c], and amino-acid activated as succinimides [183].…”

Microwave-Assisted Synthesis of Five-MemberedO,N,N-Heterocycles

“…[13,14] Kaboudin and coworkers developed two different procedures for the synthesis of 1,2,4-oxadiazole derivatives. Reaction of amidoximes and acyl chlorides with magnesium oxide [15] or alumina-supported ammonium fluoride [16] resulted in the formation of 1,2,4-oxadiazole derivatives (Scheme 1). In the other method, the authors used alkyl nitriles, acyl chlorides, and magnesiasupported hydroxyl amine hydrochloride [17] or the same reagent in the presence of potassium fluoride [18] with MW irradiation and obtained the target compounds in good yields (Scheme 2).…”

“…Microwave-assisted synthesis of 1,2,4-oxadiazoles of amidoximes under solvent-free conditions was found to be an efficient method for one-pot synthesis of 1,2,4-oxadiazole derivatives from amidoximes and acyl chlorides. The method given by Kaboudin and Navaee [15] is an easy, rapid, and high-yielding reaction for the synthesis of 1,2,4-oxadiazoles (Scheme 9). N. KAUR 1,3-Dipolar cycloadditions of nitrile oxide generated in situ on soluble polymer with a variety of imines provided a library of 4,5-dihydro-1,2,4-oxadiazoles in good yields and purity [25] (Scheme 10).…”

New one step synthesis of 3,5‐disubstituted 1,2,4‐oxadiazoles

“…These compounds can exhibit antimicotic properties [3], can act as anti-inflammatory agents [4] and were tested on their antibacterial activity against Staphylococcus Aureus, Streptococcus Pneumoniae, Escherichia Coli, Pseudomonas Aeruginosa, and Micrococcus [5,6]. Several methods are already described in the literature to synthesize 1,2,4-oxadiazoles [7], among them, the condensation of amidoximes with carboxylic acids in the presence of a coupling reagent [8] and the cycloaddition of nitrile oxides to amidoximes in solution and on solid support [9,10]. As a part of a program directed to obtain 3,5-disubstituted 1,2,4-oxadiazole molecules which can be used as corrosion inhibitors [11], we have finalized a simple new one step synthesis of the 3,5-disubstituted 1,2,4-oxadiazoles from aromatic nitriles and hydroxylamine hydrochloride.…”